The present invention relates to the detection of the Human Immunodeficiency Virus (HIV-I), the etiologic agent of Acquired Immunodeficiency Syndrome (AIDS), in serum, plasma or other body fluids. In particular, this invention describes a diagnostic test which employs a combination of unique mouse monoclonal antibodies as a probe for the detection of HIV-I core protein p24.
AIDS is an infectious and fatal disease transmitted through intimate sexual contact and exposure to contaminated blood or blood products. HIV-I includes the formerly named viruses Human T-cell Lymphotrophic Virus Type III (HTLV III), Lymphadenopathy Associated Virus (LAV) and AIDS Associated Retrovirus (ARV). HIV-I is related to a group of cytopathic retroviruses, namely lentiviruses, on the basis of in vitro characteristics, morphologic features and nucleotide sequences (Gonda et al., Science (1985) 227:177-179; Stephan et al., Science (1986) 231:589-594).
Presently, the most reliable method for the diagnosis of AIDS is testing for serum antibodies to HIV-I structural proteins. Although these tests are highly sensitive, the presence of antibodies in blood only indicates prior exposure to HIV-I and not the presence of infection with HIV-I. In addition, once a primary infection is established, a time interval of up to 6-8 weeks may elapse before people infected with HIV-I seroconvert (Cooper et al., Lancet (1985) 1:537-540; Ho et al., Ann. Int. Med. (1985) 103:880-883). During this time, virus may be actively replicating in the host, thus making the host a seronegative source of infectious blood. Therefore, there is a need to detect virus infection during the time that precedes seroconversion in order to prevent the spread of infection through blood transfusions.
The most widely used methods for detecting HIV-I in infected individuals include the isolation of virus from infected blood or blood cells and subsequent in vitro propagation of the virus in lymphocyte cultures. In vitro replicating virus may be detected by measuring reverse transcriptase (RT) levels, immunocytochemical staining of viral proteins, electron microscopy, and nucleic acid probe hybridization. In vitro cultivation and isolation of virus are labor intensive, technique sensitive and may not be practical for use as a routine diagnostic method. Recently, enzyme immunoassays have been developed to detect HIV-I antigens in serum and other body fluids of infected people (Goudsmit et al., The Lancet (1986) 2:177-180; Allain et al., Brit. Med. J. (1986) 2993:1459-1462; Caruso et al., J. Virol. Methods (1987) 17:199-210). These enzyme immunoassays are easier to perform, specific for HIV-I, and more sensitive than conventional RT assays. Through the use of these assays, longitudinal studies carried out on high risk individuals have established a definite correlation between HIV-I antigenemia, the decline of antibodies to core protein p24, and disease progression from asymptomatic seropositivity to full blown AIDS. (Paul et al., J. Med. Virol. (1987) 22:357-363; Lange et al., Brit. Med. J. (1986) 293:1459-1462; Goudsmit et al., Concise Comm. (1986) 155:558-560; Lange et al., The Lancet (1987) Feburary: 190.) In addition, a significant decrease in the level of HIV-I p24 antigen has been observed in patients treated with AZT (Chaisson et al., New Eng. J. Med. (1986) 315:1610-1611). These studies demonstrate that HIV-I core antigens may be important serological markers for initial diagnosis of infection and disease progression, and as well may provide a tool for monitoring antiviral therapy in AIDS patients.